#!/usr/bin/env node
/**
 * MCP server: Prisma schema validator (read-only).
 *
 * Tools:
 *   - validate_schema   : structural checks against a Prisma schema string
 *   - extract_models    : return model/enum names and field counts
 *
 * These are deliberately NOT a shell-out to `prisma validate` — per the
 * KIS-TOiR optimization constraints, MCP servers must be pure, synchronous,
 * read-only validators with no external deps or CLI subprocess calls.
 */

import { runMCPServer } from "./lib/mcp-server.mjs";

// Prisma schema constants
const BUILTIN_TYPES = new Set([
  "String",
  "Int",
  "Float",
  "Boolean",
  "DateTime",
  "Json",
  "Bytes",
  "Decimal",
  "BigInt",
]);

// Regex constants (compiled once, reused across invocations)
const BLOCK_RE = /^\s*(model|enum|datasource|generator)\s+(\w+)\s*\{/gm;
const INLINE_ID_RE = /@id\b/;
const COMPOSITE_ID_RE = /@@id\s*\(/;
const FIELD_RE = /^(\w+)\s+([\w?\[\]]+)/;
const RELATION_RE = /@relation\b/;

/**
 * Extremely lightweight Prisma schema parser. Not a full grammar — it
 * recognizes top-level blocks (`model`, `enum`, `datasource`, `generator`)
 * and counts fields inside model/enum blocks by line. Sufficient for the
 * structural sanity checks the orchestrator asks for.
 */
function parseBlocks(schema) {
  const blocks = [];
  let m;
  while ((m = BLOCK_RE.exec(schema)) !== null) {
    const kind = m[1];
    const name = m[2];
    const openIdx = schema.indexOf("{", m.index);
    // Walk forward to find the matching close brace. Prisma schemas do not
    // nest braces inside blocks, so a simple depth counter is enough.
    let depth = 1;
    let i = openIdx + 1;
    for (; i < schema.length && depth > 0; i++) {
      if (schema[i] === "{") depth++;
      else if (schema[i] === "}") depth--;
    }
    const body = schema.slice(openIdx + 1, i - 1);
    const fieldLines = body
      .split(/\r?\n/)
      .map((l) => l.trim())
      .filter((l) => l && !l.startsWith("//") && !l.startsWith("@@"));
    blocks.push({ kind, name, body, fields: fieldLines });
  }
  return blocks;
}

const tools = [
  {
    name: "validate_schema",
    description:
      "Validate a Prisma schema string for structural soundness: required generator and datasource blocks, at least one model, each model has an @id or @@id, referenced enums exist. Read-only; never writes files.",
    inputSchema: {
      type: "object",
      properties: {
        schema: {
          type: "string",
          description: "Full contents of schema.prisma",
        },
      },
      required: ["schema"],
    },
    execute: async ({ schema }) => {
      if (typeof schema !== "string" || schema.length === 0) {
        return { success: false, error: "schema must be a non-empty string" };
      }

      const issues = [];
      const blocks = parseBlocks(schema);

      const generators = blocks.filter((b) => b.kind === "generator");
      const datasources = blocks.filter((b) => b.kind === "datasource");
      const models = blocks.filter((b) => b.kind === "model");
      const enums = blocks.filter((b) => b.kind === "enum");

      if (generators.length === 0)
        issues.push("missing generator block (expected `generator client`)");
      if (datasources.length === 0)
        issues.push("missing datasource block (expected `datasource db`)");
      if (models.length === 0) issues.push("schema declares no models");

      const enumNames = new Set(enums.map((e) => e.name));

      for (const model of models) {
        const hasInlineId = INLINE_ID_RE.test(model.body);
        const hasCompositeId = COMPOSITE_ID_RE.test(model.body);
        if (!hasInlineId && !hasCompositeId) {
          issues.push(`model ${model.name} has no @id or @@id directive`);
        }

        // Detect referenced types that look like enums but are not declared.
        for (const fieldLine of model.fields) {
          // field definition: `name Type[?] ...`
          const fieldMatch = fieldLine.match(FIELD_RE);
          if (!fieldMatch) continue;
          const rawType = fieldMatch[2].replace(/[\?\[\]]/g, "");
          if (BUILTIN_TYPES.has(rawType)) continue;
          // If a type looks like an enum reference (capitalized, no model match),
          // warn when it is not found in declared models or enums.
          const isKnownModel = models.some((m) => m.name === rawType);
          const isKnownEnum = enumNames.has(rawType);
          if (!isKnownModel && !isKnownEnum) {
            // Might be a relation target defined later — only flag if it
            // looks enum-shaped (all caps first letter, no `@relation` on the line).
            if (!RELATION_RE.test(fieldLine)) {
              issues.push(
                `model ${model.name} field \`${fieldMatch[1]}\` references unknown type \`${rawType}\``
              );
            }
          }
        }
      }

      return {
        success: issues.length === 0,
        result: {
          blockCounts: {
            generator: generators.length,
            datasource: datasources.length,
            model: models.length,
            enum: enums.length,
          },
          issues,
        },
      };
    },
  },
  {
    name: "extract_models",
    description:
      "Extract model and enum names from a Prisma schema string, along with per-model field counts. Useful before diffing against a frozen contract.",
    inputSchema: {
      type: "object",
      properties: {
        schema: { type: "string" },
      },
      required: ["schema"],
    },
    execute: async ({ schema }) => {
      if (typeof schema !== "string") {
        return { success: false, error: "schema must be a string" };
      }
      const blocks = parseBlocks(schema);
      return {
        success: true,
        result: {
          models: blocks
            .filter((b) => b.kind === "model")
            .map((b) => ({ name: b.name, fieldCount: b.fields.length })),
          enums: blocks
            .filter((b) => b.kind === "enum")
            .map((b) => ({ name: b.name, valueCount: b.fields.length })),
        },
      };
    },
  },
];

runMCPServer({ name: "kis-toir-prisma-validator", version: "0.1.0", tools });